Fracture process zone of notched three-point-bending concrete beams

By measuring and analyzing the load-deflection curve and acoustic emission characteristics of notched three-point-bending concrete beams with different notch depths, the length of the fracture process zone (FPZ) was calculated from the difference between the equivalent crack lengths obtained by different kinds of equivalence. Then, the evolution of the FPZ was quantitatively described. It was found that length of the FPZ is not a material parameter; it is greatly influenced by the specimen size. But in a relative sense, the influence of the specimen size can be eliminated. Also, the evolution of the FPZ in specimens of different sizes is almost the same. When the crack length is small, the FPZ increases linearly with the crack extension. As the crack extends to half of the ligament, the FPZ reaches its maximum size. Thereafter, the FPZ moves ahead and shrinks, but the ratio of its length to the length of the residual ligament remains constant, approximately equal to 0.77, (C) 2000 Elsevier Science Ltd. All rights reserved.